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You can use azalea fertilizer on hydrangeas, but you need to be careful about how you use it.
Azalea fertilizer is designed for acid-loving plants, and hydrangeas absolutely fit into that category.
So if you’ve been wondering whether you can use azalea fertilizer on hydrangeas, the short answer is yes, it can work very well under the right conditions.
However, there are some important nuances about the nutrient ratios and how they affect bloom color that you should understand first.
In this post, we’ll break down exactly when you can use azalea fertilizer on hydrangeas, how it impacts your plants, and the best practices for feeding your hydrangeas with this type of product.
Let’s dig into the details.
Why You Can Use Azalea Fertilizer on Hydrangeas
Azalea fertilizer works on hydrangeas because both plants thrive in acidic soil.
The primary reason you can use azalea fertilizer on hydrangeas comes down to their shared preference for a lower pH range.
Azaleas and hydrangeas both love soil with a pH between 4.5 and 6.0, which helps them absorb nutrients efficiently.
Hydrangeas will happily take up the same type of slow-release or water-soluble feed that you’d give to azaleas.
Let’s look at why this is such a good pairing.
1. Acid-Loving Nutrient Profile
Azalea fertilizer typically has a slightly higher nitrogen content and includes sulfur or other acidifying agents.
When you use azalea fertilizer on hydrangeas, that extra nitrogen supports lush, green foliage growth.
And the acidifying elements help maintain the soil pH that hydrangeas crave.
This makes it a solid choice for feeding your hydrangeas during the early growing season.
2. Balanced Ratio for Blooms
Most azalea fertilizers have an NPK ratio like 10-8-8 or 12-6-6.
That balance of nitrogen, phosphorus, and potassium is actually very close to what hydrangeas need.
Phosphorus supports strong root development and encourages those big, beautiful blooms.
So when you use azalea fertilizer on hydrangeas, you’re giving them a meal that promotes both green growth and flower production.
3. Slow-Release Options Are Gentle
If you choose a slow-release azalea fertilizer, it’s even safer for hydrangeas.
Slow-release formulas feed your plants gradually over several weeks or months.
This prevents the risk of burning the roots, which can happen with liquid fertilizers applied too often.
Hydrangeas respond beautifully to this steady, gentle feeding approach.
How Azalea Fertilizer Affects Hydrangea Bloom Colors
Before you run out and use azalea fertilizer on hydrangeas, you should understand how it impacts flower color.
This is especially important if you have bigleaf hydrangeas, which change color based on soil pH.
Using azalea fertilizer can actually shift the color of your hydrangea blooms.
1. Acidic Soil Turns Blooms Blue
When you use azalea fertilizer on hydrangeas, the acidifying effect lowers the soil pH.
Lower pH means more aluminum becomes available to the plant’s roots.
And aluminum is the key element that turns hydrangea blooms a vivid blue.
So if you want blue flowers, azalea fertilizer is your friend.
2. Higher pH Keeps Blooms Pink
If your soil is naturally more alkaline, your hydrangeas will produce pink blooms.
Using azalea fertilizer on hydrangeas in alkaline soil won’t necessarily change that right away.
You’ll need consistent acidification over months to really shift the pH.
So if you love pink hydrangeas, you might want to skip this fertilizer or use it sparingly.
3. White Hydrangeas Stay White
White hydrangeas don’t respond to soil pH at all when it comes to bloom color.
So you can freely use azalea fertilizer on hydrangeas that produce white flowers.
The fertilizer will still feed the plant well, just without altering the bloom appearance.
That’s a nice peace of mind if you’re growing a white variety like Annabelle or Incrediball.
When to Use Azalea Fertilizer on Hydrangeas
Timing is everything when you decide to use azalea fertilizer on hydrangeas.
Applying it at the wrong time can do more harm than good.
Here’s the best schedule to follow.
1. Early Spring Application
The ideal time to use azalea fertilizer on hydrangeas is in early spring.
This is just as new growth begins to emerge from the stems.
Applying a slow-release granular formula at this point gives your plants the nutrients they need to wake up strong.
It also sets the stage for a robust blooming season later in the summer.
2. Light Feeding in Late Spring
You can do a second, lighter application about six weeks after the first.
This helps sustain growth without overfeeding.
Keep in mind that too much fertilizer can lead to lots of leaves but very few flowers.
So don’t go overboard with a heavy second dose.
3. Avoid Feeding After Mid-Summer
Never use azalea fertilizer on hydrangeas after late July or early August.
Late feeding encourages new soft growth that won’t harden off before winter.
This tender growth is highly susceptible to frost damage.
So stop fertilizing by mid-summer to keep your hydrangeas safe.
How to Apply Azalea Fertilizer on Hydrangeas Correctly
Getting the application method right is just as important as the timing.
Here’s how to do it properly.
1. Water the Soil First
Always water your hydrangeas deeply a day before you plan to fertilize.
Moist soil helps prevent root burn when you apply the fertilizer.
You can use azalea fertilizer on hydrangeas safely as long as the roots aren’t bone dry.
2. Apply Around the Drip Line
Don’t pile fertilizer against the main stems.
Instead, spread it evenly around the drip line, which is the outer edge of the leaf canopy.
This is where the feeder roots are most active.
Work the granules lightly into the top inch of soil.
3. Water Again After Application
After spreading the fertilizer, water the area again thoroughly.
This helps dissolve the granules and carries the nutrients down to the root zone.
You can use azalea fertilizer on hydrangeas every season with this method and see great results.
Alternatives to Azalea Fertilizer for Hydrangeas
While you can use azalea fertilizer on hydrangeas, you also have other good options.
Some gardeners prefer a fertilizer formulated specifically for hydrangeas.
Others like to go the organic route.
1. Hydrangea-Specific Fertilizers
These products are designed with the exact nutrient needs of hydrangeas in mind.
They often include extra magnesium or iron to keep foliage vibrant.
But honestly, azalea fertilizer performs just as well in most cases.
2. Organic Compost and Mulch
You don’t have to rely on synthetic fertilizers at all.
Adding compost or aged manure around your hydrangeas enriches the soil naturally.
You can use azalea fertilizer on hydrangeas as a supplement, but compost alone can be enough.
3. Espoma or Miracid Products
If you want a product that’s both acidifying and gentle, look for Espoma Holly Tone or Miracid.
These are similar to azalea fertilizer and work wonderfully on hydrangeas.
So you have plenty of choices if you don’t want to use azalea fertilizer specifically.
So, Can You Use Azalea Fertilizer on Hydrangeas?
Yes, you can use azalea fertilizer on hydrangeas with great success.
It’s a perfect match because both plants love acidic soil and similar nutrient ratios.
Just be mindful of the bloom color changes that may occur with acidic feeding.
And always stick to a proper feeding schedule in spring and early summer.
You can use azalea fertilizer on hydrangeas to get lush foliage, healthy roots, and gorgeous blooms all season long.
Just don’t overdo it, and always water well before and after applying.
With a little care, your hydrangeas will reward you with a spectacular display of color.
Happy gardening.